问题
选择题
----Sixteen-year-olds should not be allowed to drive a car.
----I agree. They are ____________.
A．too serious
B．not serious enough
C．too calm
D．not enough serious
答案
答案：B
题目分析：句意：16岁不应该允许开车。我同意，他们还不够认真。Enough足够，在修饰形容词时放在形容词后面，修饰名词时放在名词前面。再结合题意选B。